The invention concerns a motor suspension for fans, preferably axial-flow fans, with an air grille with radially extending braces that connect grille rings, positioned coaxially to each other, with each other as well as a method for producing an air grille of such a motor suspension.
Motor suspensions are known whose air grilles comprise grille rings that are coaxially positioned relative to each other and are connected by radially extending braces with each other (DE 10 2009 025 025 A, DE 23 45 539 A. DE 101 11 397 A, DE 197 53 373 A). The radial inner ends of the braces are embodied either as fastening elements for connection with the motor, or are connected to a fastening disc which is connected with the fan. The radial outer end of the braces has holding elements (DE 101 11 397 A) which serve for receiving connecting means to the fan. The air grilles have in axial section straight areas and the radial inner and outer areas extend in opposite directions at a slant and adjoin at an obtuse angle a straight middle area. Such air grilles can be produced only with complex methods because for each of these grille areas an individual welding device and thus also an individual welding process are required.
Because in the operation of the fan noises can occur, it is known to produce the radially extending braces of flat sections which are positioned according to an average swirl component at an angle to the longitudinal axis of the fan (DE 10 2009 025 025 A). It is also known to form the sections between the radial outer end and radial inner end of the support braces out of the plane of the flat section so that their edges connected with the grille rings are maintained as straight lines. However, this causes the production and the configuration of the air grille to be very complex.
For avoiding flow-caused noises it is further known (DE 197 53 373 A) to configure the air grille in the manner of kind of an air guide wheel with blade-like vanes that extend about a certain axial air guiding length and are essentially arranged approximately radially. The vanes are arranged in at least two concentric circular rows and the number of the vanes is larger in the outer circular row than in the neighboring inner circular row. Such an embodiment of an air grille is constructively very complex and this makes the production of the air grille more expensive.
Finally, it is also known (DE 101 11 397 A) to push comb-like damping means onto the coaxial grille rings.
The object of the invention is to configure the motor suspension of the aforementioned kind and the method of the aforementioned kind in such a way that in a constructively simple and inexpensive manner an optimum noise and vibration reduction is achieved during operation of the fan.